The present invention relates to a grinder pressing device.
Pressing force applied to an object to be ground by a grinder considerably affects grinding performance, grinding accuracy, life of the grindstone, and the like, and therefore grinding operation by a robot is carried out so as to maintain pressing force predetermined by various means.
There are types of grinder device; an electric grinder and an air grinder. In the former grinder, pressing force is controlled by a servomotor by determining pressing force applied to the object by a grindstone according to current of a grinder motor. In the latter grinder, pressing force is controlled by giving a command to a robot by using a six-axis sensor, for example.
However, in such controlling methods of pressing force, both the devices per se are expensive and, especially in the method of giving the command to the robot by using the six-axis sensor, control is complicated.
It is hence an object of the present invention to provide a grinder pressing device which is, irrespective of types of grinder, inexpensive and capable of compensating wear of a grindstone and/or a slight displacement of an object to be ground.
In a grinder pressing device according to the present invention, one of a bottom portion of a cylinder main body and a piston rod of an air cylinder in a vertical posture is attached to a fixed plate and the other is attached to a movable plate disposed below the fixed plate, one of a guide table and a guide is mounted on a movable plate side and the other is mounted on an outer peripheral face of the cylinder main body. The guide table is guided on the guide in a vertical direction under the rolling frictional condition through balls. In the air cylinder, hermeticity between outer peripheral walls of a piston and the piston rod and a structural wall of the cylinder main body side is provided by metal seals and friction coefficients between the walls is set low, and the piston rod is supported by a ball bushing in a large area so as to be movable forward and backward. A grinder is mounted to the movable plate directly or through another member, and pressing force of the grinder to an object to be ground can be controlled by adjusting air pressure of upper and lower cylinder chambers separated by the piston.
Moreover, a grinder pressing device of the present invention includes a hanging member having a grinder mounting portion and a partition plate, upper and lower bellows cylinders fixedly disposed on upper and lower faces of the partition plate, and a retaining member for maintaining a constant distance between an upper face of the upper bellows cylinder and a lower face of the lower bellows cylinder. The grinder pressing device is used in a manner that the retaining member is fixed to a fixed portion F or a robot output portion, that a grinder is provided on the grinder mounting portion, and that the upper and lower bellows cylinders are supplied with air of respectively predetermined pressure.